Fluid-pressure operated device



Nov. 15, 1960 P. SCHEFFLER 2,960,097

FLUID-PRESSURE OPERATED DEVICE Filed Jan. 29, 1957 LLIUIIIIIIIIIIII] INVENTOR flirrpfzwiraf 2,960,097 FLUID-PRESSURE OPERATED DEVICE Peter Schefiler, Dessau, Germany, assignor to VEB Junkalor, Dessau, Germany Filed Jan. 29, 1957, Ser. No. 636,939- Claims priority, application Germany May 9, 1956 7 Claims. (Cl. 137-82) This invention relates to improvements in devices for pneumatically amplifyingpressures, particularly for the purpose of measuring smalltchanges in pressure or. small forces.

Pneumatic pressure converters are commonly used for amplifying small and often minutest pressure forces, or variations in pressure forces. In such conventional converters, the air or gas pressure to be amplified is directed upon an impactplate which is movably suspended in as friction-free a manner as'possible. This movable impact plate is mounted and directed to face a nozzle communicating with the conduit containing the air or gas to be measured and from which a stream of the air or gas blows ontothe impact plate. By the deflection of the impact plate, .a counter force of equal magnitude is produced and canbe measured. The gap between the impact plate and the nozzle at any given time depends upon the force ofthe air .or gas stream emitted by the nozzleand impinging on the impact plate, and also upon the primary pressure of the air 'or gas, that is to say the pressure within the main conduit. This gap between impact plate and nozzle serves to produce the amplifying force.

In the use of conventional converters as above described, it is often desirable for purposes of measuring or regulating the pressure of air or gas in a conduit, to

hold the dissipation or escape of the air or gas to a minimum. At the same time it is essential to maintain an exact proportionality or ratio between the weak primary forces or pressures in the air or gas conduit, and the air pressures emitted at the nozzle. In addition, it is also of prime consideration to insure that the movement of the amplifying device which is measured, is as independent as possible from the flow velocity of air or gas or from the primary source pressure 'within the conduit between the pump and the choke, which latter is located in the conduit before the nozzle. The presence of the above considerations presents difliculties in the use of conventional pressure amplifying devices.

An object of the present invention, therefore, is to provide an amplifying device which is of greatly increased sensitivity so that the minimum air pressure or gas pressure necessary for amplifying is materially reduced, and in which the aforementioned requirements of proportionality and independence from the pressure source of the conduit or flow velocity are easily attained. The velocity of flow of the air or gas in the conduit and in the nozzle can be held to a very small value, so that the pressure being amplified is substantially a static pressure.

The aforementioned objects are achieved by substituting for the conventional impact plate, a ball which partially protrudes within the mouth of the conduit outlet pipe and forms therewith an annular air or gas outlet opening. By this arrangement, the flow velocities in the conduit and outer pipe may be held to such a small value that practically only static pressure is acting on the ball and is amplified and measured by the device.

While the ball is maintained in the mouth of the nozzle so as to provide a minimum annular gap constituting the annular air or gas outlet opening, it is desirable,

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ample freely floating in the air stream, so as to avoid metallic contact and friction. To approximate such a mounting, the invention provides a surface which is selfaligning to a horizontal position, and the ball rests freely upon this surface. This ball-supporting surface is preferably in the form of the top Wall of a container which has an open bottom end. The container is preferably in the form of an elongated cylinder, the top wall of which is suspended on an upstanding point carried by a balance beam. The container is constructed so that its center of gravity is located well below its point of suspension, alternatively, instead of placing the ball on a horizontal surface and directing the air or gas upon it from above, it is also possible to direct the outlet or nozzle opening of a conduit upwardly and set the ball on the inner surface of the cylinder.

Additional objects and advantages of this invention will become apparent in the course of the following specification when taken in connection with the accompanying drawings, in which:

Fig. 1 is a schematic representation of a pressure amplifying device made in accordance with the invention; and

balanced upon a support 13. The balance arm may be.

suspended by other equivalent means, as by a torsion suspension. The balance arm or beam 1 carries at one end an upstanding point -2 and at the other end an adjustable counter-weight 14. The small force or small change of pressure which is to be measured is applied to beam 1 at point 25 as indicated by arrow 26.

A container 3 is suspended and balanced on the point 2. Said container 3 is preferably of a cylindrical shape having a top Wall 15 and an open bottom end. The end of the balance arm 1 extends through an appropriate opening in the side wall of the container 3 and the bottom surface of the top wall 15 is centered upon and balanced upon the point 2. The center of gravity of the cylindrical container 3 is located well below its point of suspension 2 and for this purpose said cylinder 3 may be weighted at its bottom end as indicated at 16 in Fig. 1. It will be apparent that because of this low center of gravity, the container 3 will maintain itself in a vertical position regardless of the position to which the balance arm 1 may rock, and the top wall 15 will then always be maintained with its flat upper surface in a horizontal position.

A ball 5 rests freely upon the flat upper or outer surface of the container top wall 15. The depending discharge nozzle 6 of the air or gas conduit 17 is located directly above and proximate to the ball 5. Compressed air or a gas is produced by a small membrane pump 7 which communicates with the conduit 17 through a restricted orifice 22. A pressure relief valve 23 maintains a constant pressure in the duct between pump 7 and orifice 22. Conduit 17 is connected to a recording pressure gage 24. The compressed air or gas produced by the pump 7 is carried through the nozzle 6 and impinges on the ball 5 urging the end of the balance arm 1 carrying the container 3 to be deflected downwardly against the force applied on beam 1 at point 25, which force is to be measured on a recording device or the like.

A tank 18 containing water or other suitable liquid is located beneath the cylinder 3, and an immersion bell 4 is inverted and immersed partially into the liquid 8 so that an air pocket is formed in the bell 4 above the level of the water or liquid 8. A conduit 9 extends within the tank 18 and opens within the bell 4 above the level of the liquid 8. The end of balance arm 1 beneath the point 2 is connected to the bell 4 by means of a rod 19. The air pressure within the bell 4 may be raised or lowered by introducing or extracting air through the conduit 9, whereby the depth of immersion of the bell 4 in the liquid 8 may be varied. In this way, the originally-set vertical position of the ball 5 relative to the mouth of the nozzle 6 may be varied as desired. This in turn results in a considerably amplified variation in the recorded conduit pressure. The immersion bell '4 also serves to dampen the rocking movement of the balance arm 1. The point of attachment of the balance arm 1 to the immersion bell 4 may optionally be transferred to another location on the arm 1 than that shown in Fig. l.

The construction described above insures that the ball S'always adjusts itself to the air stream emitted by the nozzle 6 in such a manner that it is centered on the mouth of the nozzle 6. An exact annular gap is thus formed between the mouth of the nozzle 6 and the surface of the ball 5 which projects into said mouth. Since the ball rests upon the flat upper surface of the container top wall 15 and this surface is self-aligning to a horizontal plane because of its pivot mount on point 2, the ball 5 will be located directly in the center of the air outlet opening provided by the mouth of nozzle 6 even when the point 2 is not exactly in axial alignment with the center of the air outlet opening. To prevent the ball from falling off its flat support surface, an upstanding rim or flange 2% may be provided on the container top wall 15.

The positioning of the ball 5 rests freely on the wall 15 and the balanced pivot mountings provided by points 2 and 12, permits a pressure amplification in which friction losses are reduced to an absolute minimum and are negligible. The annular gap formed by ball 5 with the mouth of nozzle 6 may be held to such a small size that even the most minute forces applied to beam 1 at point 25 will be effective to displace the ball 5 and cylinder 3 vertically so that the corresponding pressure changes in conduit 17 will reflect an amplification of these low forces to a degree never attained heretofore. In addition, the aforementioned annular gap may be initially set to such small size that even with extremely low pressures, the pressure loss of dissipation from the system due to flow of the gas or the air through the gap, will be minimized.

Fig. 2 shows a modification of the amplifying device in which instead of placing the ball on a flat surface and directing the stream of air or gas downwardly thereupon, the air or gas may be directed upwardly against the ball from underneath. In this instance the ball 5 is located directly above the outlet opening of a compressed air or gas conduit 10. The ball 5 rests against the inner or lower surface of the top wall 21 of a container 11 which is also of cylindrical shape. The container 11 preferably has its center of gravity located well below the outlet opening of the conduit 10. With the passage of air or gas in the conduit 10, an exact annular gap will be formed between the ball 5 and the mouth of the conduit 10. To keep this annular gap of a minimum size, the necessary counter force may be directed from above downwardly on the cylinder 11 as by a weight. The counter force may also be produced magnetically.

While preferred embodiments of this invention have been shown and described herein, it is obvious that numerous changes, additions and omissions may be made without departing from the spirit and scope of the invention.

What is claimed is:

1. A pneumatic pressure amplifier for producing a recordable fluid pressure change within a conduit in response to a force the magnitude of which is to be measured, said amplifier comprising a source of fluid under pressure communicating with said conduit, a restricted orifice interposed between said conduit and said source of fluid, nozzle means having a circular horizontal opening and communicating with said conduit for discharge of said fluid, a spherical blocking member arranged subjacent said circular nozzle opening for engagement therewith, horizontally aligned flat support means for supporting said spherical member, said support means being movable vertically responsive to said force for engaging said spherical member and said nozzle opening, and aligning means for maintaining horizontal alignment of said flat support means, said aligning means comprising a pointed support vertically movable rosponsive to said force, a vertically extending member fixedly connected near the upper end thereof to said horizontal support means and weighted near the lower end thereof, said vertical member being supported on said pointed support above the combined center of gravity of said vertically extending member, said fiat support means, and said spherical member, for horizontal alignment of said flat support means.

2. A pneumatic pressure amplifier as set forth in claim 1, said vertically extending member being of substantially cylindrical shape, said fiat support means forming the top wall of said cylindrically-shaped member.

3. A pneumatic pressure amplifier as set forth in claim 1, said pointed support being fixedly connected to a substantially balanced beam horizontally and pivotally supported intermediate the ends thereof, said force acting upon said beam for pivoting movement thereof whereby said sphere is moved toward said nozzle opening when said force is applied to said beam.

4. A device for pneumatically translating measured values and for pressure amplification comprising a conduit having an outlet, a source of fluid under pressure in said conduit, means connected to said conduit for measuring the pressure in said conduit, a movable balance member, a conical upstanding pivot on one end of said balance member, a platform horizontally supported by gravitation on said pivot, a member depending from said platform below said pivot whereby a pendular action is exhibited by said platform and said member, said platform being positioned below said conduit outlet, a throttling ball supported by said platform for varying the pressure in said conduit in response to forces on the other end of said balance member.

5. A device as set forth in claim 4 wherein said depending member is in the shape of a cylinder, and further comprising a recess of conical cross-section below said platform for receiving said pointed pivot.

6. In a pneumatic device having a source of pneumatlc pressure, a conduit, a descending orifice in said conduit, a throttling ball adapted to be placed in the path of fluid being ejected by said orifice, a pendular support for said ball including a platform, means locating the center of gravity of said support 'below said platform, and pivoting means supporting said support at the underside of said platform, whereby pendular action of said support maintains said platform in a horizontal position.

7. In a device as set forth in claim 6, said pivoting means including a conical point, a fulcrum and a lever arm supporting said point and mounted on said fulcrum.

References Cited in the file of this patent UNITED STATES PATENTS 2,339,469 Emanuel Jan. 18, 1944 2,669,247 Olah Feb. 16, 1954 2,732,849 Rosenberger et al. Jan. 31, 1956 2,775,253 Engel Dec. 25, 1956 2,804,877 Rosenberger Sept. 3, 1957 FOREIGN PATENTS 730,965 Great Britain June 1, 1955 

